“Smart semiconductor switches” often include, besides the semiconductor switch, driver circuitry for driving the semiconductor switch on and off in a defined manner as well as interface circuitry for allowing communication with external components such as micro controllers, which control the operation of the smart switch at a higher abstraction level. One example of such a smart switch is Infineon's four channel high-side smart power switch BTS5682E (see BTS5682E, Data Sheet, Rev. 1.0, 2008-01-22) which may typically be employed in automotive light control applications.
In many applications smart power switches have to be designed to withstand transient electrical disturbances due to inductive or capacitive coupling as well as electrostatic discharges (ESD). For example, smart power switches have to be tested in accordance with the ISO 7637-2 standard. Such “transient immunity tests” are performed to check whether the device under test is able to withstand certain transient disturbances which may occur at the input or output pins. ISO 7637-2 defines some standard pulses which represent realistic disturbances that may occur in automotive applications.
As every smart switch has to fulfill some requirements with respect to susceptibility to transient disturbances, there is generally a need to provide smart power switches with efficient protection circuitry which guarantee a high immunity to relevant transient disturbances.